DENDY— HOMOSCLEROPHORA AND ASTROTETRAXONIDA 267 



in his Tethea rohusta [1873 a] as being very large, but they are only one-fifth the diameter 

 of those of the present species, according to his measurements and figure. In Donatia 

 tylota, however, they seem to be nearly as large as in D. stella-gy-andis. 



Register No., Locality, die. cvi. 5, Amirante, 13.10.05, E. 16, 39 fathoms. 



Family Chondrosiidae. 



Corticate Astrotetraxonida with complex canal system and small flagellate chambers. 

 Without megascleres. Microscleres, when present, euasters. 



This family, as at present understood, comprises only the two genera, Chondrilla and 

 Chondrosia. These may both be regarded as reduction forms derived from some stellettid 

 ancestor such as Aurora. The spherasters of Chondrilla closely resemble those of Aurora, 

 but the megascleres have entirely disappeared. In some specimens of Chondy-illa mixta 

 the asters have already become very rare, and these seem to lead the way to the genus 

 Chondrosia, in which all spicules have entirely disappeared. 



Genus Chondrilla Schmidt [1862]. 

 Chondrosiidse with microscleres (euasters of one or more kinds). 



23. Chondrilla australiensis Carter. 

 (Plate 48, fig. 6.) 



Chondrilla australiensis Carter [1873 c]. 

 Chondrilla australiensis Lendenfeld [1886 a]. 

 Chondrilla australiensis Lindgren [1897, 1898]. 

 Chondrilla australiensis Dendy [1905, 1915]. 

 Chondrilla australiensis Hentschel [1909, 1912]. 



This species is characterised by the presence of two kinds of aster, spherasters 

 (Plate 48, fig. 6 a) about 0"03 mm. in diameter, and oxyasters (fig. 6 6) of somewhat 

 smaller size with roughened and sometimes slightly branched rays. The spherasters are 

 characteristically cortical in distribution and the oxyasters characteristically choanosomal, 

 but spherasters occur also in the choanosome and oxyasters in the cortex. 



It seems possible also that the light colour as compared with some other species may 

 be a more or less constant character. Carter originally described the species as "of a 

 dirty yellow or buff" colour." Lendenfeld copies this. Hentschel speaks of the colour of 

 specimens from S.W. Australia as mostly clear greyish-yellow, almost white in some small 

 specimens, but in places brown to black-brown. The Ceylon specimens collected by 

 Prof Herdman were of a greyish colour (in spirit). The " Sealark" specimens range from 

 almost quite white all over (R.N. XLiii. 2) to light brown (in spirit) ; they form flattened 

 or lobular crusts of the usual appearance. R.N. xxxi. 1 is growing upon a specimen of 

 Dercitopsis minor. 



In some specimens (R.N. XLiii. 2, 4) the oxyasters are so nearly smooth as to resemble 

 very closely those of C. mixta. 



Previously known Distribution. Port Jackson, E. Coast of Australia (Carter, Lenden- 

 feld) ; Shark's Bay, S.W. Australia (Hentschel); Okhamandal and Ceylon (Dendy); coast 

 of Cochin China (Lindgren) ; Aru Islands (Hentschel). 



34—2 



